Heat the oil in a frying pan over a medium heat and cook the onion until translucent, stirring occasionally. Add the garlic and anchovies and cook for a minute, stirring to break up the anchovies. ADD the chili flakes, capers, olives, tomatoes, crushed tomatoes, tomato paste, and pepper, and bring to the boil. Reduce the heat to medium-low and simmer, uncovered, for 10 minutes, stirring occasionally. While the sauce is simmering, cook the pasta. Top drained pasta with sauce and parsley. Serve with fresh grated parmesan.